Production, purification, and characterization of alkaline protease from Aspergillus flavus and its compatibility with commercial detergents

Aspergillus flavus was used to produce alkaline protease. Solid state fermentation (SSF) strategy was adopted to explore the most favorable physical and nutritional conditions for enzyme production. Maximum production was achieved at pH 6.0 and a temperature of 30 °C after 84 h of growth period. For the optimization of the chemical parameters, different carbon and nitrogen sources were used including glucose, fructose, sucrose, ammonium sulphate, and urea. Maximum production was observed with 0.3% concentration of all the compounds. Ammonium sulphate salting out and gel chromatography was used to purify the enzyme. The enzyme was completely precipitated out at 80% saturation. The value of Vmax was 3.9 U/mL, while the value of Km was 1.9 mg/mL. The enzyme was tested for its compatibility with a few famous detergents available on the market. With the alkaline protease under study, the enzyme displayed a maximum retention of its activity i.e. 80.8% in the presence of commercial detergent Surf excel. The activity dropped down to 61.5% when the enzyme was allowed to work in the presence of another locally used detergent, i.e., Bonus. Protease production from A. flavus was carried out on rice bran and wheat bran and the wheat bran gave better results.